1. Field of the Invention
This invention relates to a lubrication means for an internal combustion engine.
More particularly, this invention relates to a lubrication pumping apparatus actuated by one or more reciprocating piston rods to assure lubrication of the crankpin bearing and the wrist pin bearing of an internal combustion engine.
2. Description of the Prior Art
Many different ways to lubricate the various rotating parts of an internal combustion engine are well-known in the art. For example, with internal combustion engines having oil reservoir sumps, lubricating holes are provided in the rod cap of a piston rod to supply lubricant to the rod crankpin bearing of the crankshaft during operation of the engine. These passages typically are transverse to an axis of the crankpin. The openings may be holes drilled through the rod bearing cap or a slot may be provided at the bottom of the rod cap to allow lubricant to pass into the crankpin bearing areas. This method is sufficient to lubricate the rod crankpin bearing where oil in the sump submerges the crankshaft/crankpin as the crankshaft revolves within the engine crankcase or engine block.
There are other methods that force lubricant from a pump within an oil sump of an internal combustion engine to various bearing surfaces. For example, oil is forced through a borehole in the crankshaft into the rod crankpin bearing. These types of engines typically have a motor-driven oil pump that supplies lubricant under pressure to all the bearings.
U.S. Pat. No. 2,280,296 teaches a means to lubricate a rod/crankpin bearing by providing a series of spiral lubricating grooves down the bearing surfaces of a crankshaft that terminates at the crankshaft flywheel. A port, directed from the spiral lubricating grooves through the crankpin to the interior of the bearing surfaces formed between the crankpin and the rod cap, provides a lubricating path to this bearing, thus providing lubricant to the bearing during operation of the engine. Lubricant is drawn from a sump at the bottom of the crankcase, up the front of the engine to the forward end of the crankshaft and, from there, down the spiral grooves in the crankshaft to the rod/bearing crankpin. While a means is provided to pump lubricant to a rod/crankpin bearing, there is no means to lubricate the wrist pin connecting the rod to the piston.
U.S. Pat. No. 2,936,748 describes a means for lubricating a two-cycle engine. This invention provides a means to collect oil droplets that separate from a fuel/oil mixture and directs this separated and collected oil to bearing surfaces within the engine. These two-cycle engines depend for their lubrication upon the collection of oil entrained in the stream of gaseous fuel charge (fuel/oil mixture) whereby the lubricant may be selectively directed to critical lubricating points. This patent teaches the utilization of a pressurized lubrication system for two-stroke engines. Collected oil is routed, under pressure, from a crankcase of the engine and is forced into a chamber formed in the crankshaft and, from there, to a port leading from the crankshaft to the rod/crankpin bearings, thus feeding this collected lubricant, separated from the fuel, to this particular bearing.
This patent provides an oil separation system and a separate pump within the crankcase to direct the separated and collected oil to various bearing surfaces, such as the bearing of the crankshaft and the rod/crankpin bearing. There is, however, no means to direct lubricant to the wrist pin bearing.
The present invention goes beyond the state of the art in that a lubricant pumping means is provided by utilizing the reciprocating and circular motion of the piston rod to collect and drive lubricant entrained in a fuel/oil mixture within the crankcase of a two-cycle engine to the crankpin and wrist pin bearings. When the piston moves up its cylinder wall, a partial vacuum is created within the crankcase which draws a mixture of fuel and lubricant into the crankcase chamber. The rod connected between the crankpin of the engine crankshaft and the wrist pin of the piston forms an internal passage or longitudinal bore that communicates between the crankpin rod bearing and the wrist pin rod bearing. A fuel/oil rod inlet opening or slot is positioned between the crankpin and the wrist pin. The inlet slot is preferably positioned in the bottom one-third of the rod nearest the crankpin bearing and is oriented parallel to the shank of the rod. The slot intersects the bore in the rod and communicates between the interior of the crankcase chamber and the interior passage in the rod. Again, as the piston moves up the cylinder, the partial vacuum created within the chamber draws a mixture of fuel and oil into the chamber and, from there, into the inlet slot in the side of the rod transverse to the longitudinal bore in the rod shank. Fuel and oil is "scooped" into the interior of the rod as the rod revolves around the crankshaft flywheel. When the rod rotates clockwise from about the three o'clock position to about the nine o'clock position, fuel is scooped into the inlet slot to the rod interior. As the engine is operating, the interior of the rod eventually fills with lubricant, thus assuring a means to lubricate both the crankpin bearing and the wrist pin bearing from within the interior of the rod while maintaining the temperature of the rod within a safe range (especially during high RPM conditions) to prevent potential catastrophic failure of the rod. A protrusion formed by the rod at an exit end of the opening or slot within the internal bore diverts the lubricant within the rod around the opening, thus substantially preventing the lubricant from exiting the interior of the rod. Inertial forces generated by the reciprocating piston drives fuel and oil contained within the bore in the rod into the crankpin and wrist pin bearing surfaces under high pressure during engine operation.
An alternative embodiment of the present invention consists of a rod with a longitudinal bore through the center of the rod. A pair of fuel and oil inlet ports are positioned in the face of the rod in axial alignment with the wrist pin and the crankpin of the rod. The fuel and oil passage ports are positioned on one or both faces of the rod as opposed to a passage port on a side of the rod as previously described. The fuel and oil inlet ports on one or both sides of the rod communicate between the crankcase chamber and the internal longitudinal bore in the rod. The ports are preferably positioned about halfway between the wrist pin and the crankpin. The ports through a face of the rod are additionally angled from the outside face of the rod toward the crankpin end and toward the wrist pin end of the rod. The angle of the inlet ports is between fifteen and forty-five degrees. A scoop is also provided above and below the inlet ports on the face of the rod to provide a means to collect fuel and oil entrained within the crankcase and on the surface faces of the rod as the crankpin moves through each revolution. By positioning the inlet ports on one or both faces of the rod--the dual passageways being in alignment with the crankpin or the wrist pin--as the rod rotates and reciprocates within the engine, the lubricant within the longitudinally extending bore in the rod cannot, for example, readily escape through a port positioned in the side of the rod as is taught in the other embodiment of this invention.
Insofar as the inventor is aware, no one has utilized the reciprocating and circular motion of a rod/piston combination to direct lubricant into the interior of a rod to lubricate and cool the crankpin and the wrist pin bearings from within a cavity formed in the rod. These types of bearings are especially subjected to intense heat and frictional loads which, in turn, may catastrophically fail these bearing surfaces under extreme conditions without adequate lubrication and cooling. For example, miniature two-cycle engines typically used in model boats and aircraft are capable of operating in a revolution per minute range between 2,000 and 30,000 RPM's. These types of engines are especially vulnerable to rod failure when operating at high RPM's due to intense heat and sparse lubrication.